1. Field of the Invention
The present invention relates to a zero insertion force (ZIF) socket for electrically connecting an electronic package such as a pin array (PGA) chip with a circuit substrate such as a printed circuit board (PCB), and particularly to a ZIF socket having a base with resiliently deformable walls.
2. Description of the Prior Art
Electrical sockets are widely used in the connector industry for electrically connecting central processing units (CPUs) to printed circuit boards (PCBs) in personal computers (PCs). One kind of electrical socket is disclosed in xe2x80x9c1996 IEEE 46th Electronic Components and Technology Conferencexe2x80x9d and in U.S. Pat. No. 4,988,310. Referring to FIGS. 6 and 7, the electrical socket is designed for electrically interconnecting a CPU 8 with a PCB (not shown). The socket 9 comprises a dielectric base 91, a cover 92 slidably mounted on the base 91, and an actuation device 93 engaged with the base 91 and the cover 92. The CPU 8 comprises a multiplicity of pins 81. The CPU 8 is attached on the cover 92, with the pins 81 extending through the cover 92. By turning the actuation device 93, the cover 92 moves along the base 91 between a closed position and an open position. The CPU 8 and the PCB correspondingly electrically connect or disconnect. The base 91 comprises a multiplicity of passageways 96 for receiving a multiplicity of conductive contacts 95. The base 91 has a wall 97 between each two adjacent passageways 96. The socket 9 is used to transmit electrical signals by way of electrical current between the CPU 8 and the PCB. The accompanying voltage may be so high that it causes the electrical current to jump across the wall 97 from one contact 95 to another contact 95. This frequently results in failure of signal transmission between the CPU 8 and the PCB, and even damage to the CPU 8.
To solve this problem, the walls 97 of the socket 9 are designed to be thick enough to space the contacts 95 apart a sufficient distance. This minimizes the risk of electrical current jumping from one contact 95 to another contact 95. However, the pins 81 of the CPU 8 may not be precisely positioned in the passageways 96. In particular, the CPU 8 may be pushed too far along the base 91 by the cover 92. As a result, the pins 81 may bear against the walls 97 of the base 91. Because the walls 97 are thick and rigid, the pins 81 are liable to be deflected and even damaged by the walls 97. In addition, an unduly large amount of material is required to make the base 91 having the thick walls 97. Furthermore, the walls 97 make the base 91 unduly heavy. U.S. Pat. Nos. 5,443,591 and 5,456,612 disclose conventional sockets which have disadvantages similar to the disadvantages described above.
A new electrical socket which overcomes the above-mentioned problems is desired.
An object of the present invention is to provide a ZIF socket having a base with walls that minimize the risk of accidental damage to pins of an associated CPU.
Another object of the present invention is to provide a ZIF socket having a base with walls whereby manufacturing and transportation costs of the socket are reduced.
To achieve the above objects, a ZIF socket of the present invention is for electrically connecting a central processing unit (CPU) with a mother board. The socket comprises a dielectric base, a cover slidably mounted on the base, and a multiplicity of terminals received in corresponding passageways defined through the base for electrically connecting pins of the CPU with the mother board. The cover defines a multiplicity of holes therein, for receiving the pins of the CPU therethrough. The base has a multiplicity of walls respectively between every two adjacent passageways along a direction of sliding of the cover. A multiplicity of blind cavities is respectively defined in the walls, with openings of the cavities facing the cover. When the cover is slid to a closed position, the CPU may be pushed too far along the base by the cover. When this happens, some pins may bear against corresponding walls of the base. Because the cavities are defined in the walls, the walls deflect under pressure from the pins, rather than resisting such pressure. Thus the risk of damage to the pins when the CPU is pushed too far by the cover is minimized.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which: